GlaxoSmithKline, the UK-based pharmaceutical company, failed to adequately promote the anti-flu drug Relenza and wrote off its development while long concealing the decision from Biota, its Australian partner, according to court filings made public Thursday.

Internal GSK documents show that it discussed an “exit strategy” from Relenza at least as early as May 2000 but decided to blame the decision on a “poor flu season” after recognising the financial damage that withdrawal could cause to Biota.